Misplaced Pages

Parthenogenesis is a form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. It occurs in many eukaryote taxa.

Taxa

Oomycetes

Apomixis appears to occur in Phytophthora, an oomycete. Oospores from an experimental cross were germinated, and some of the progeny were genetically identical to one or other parent, implying that meiosis did not occur and the oospores developed by parthenogenesis.

Velvet worms

No males of Epiperipatus imthurni have been found, and specimens from Trinidad were shown to reproduce parthenogenetically, making it the only velvet worm known to use parthenogenesis.

Rotifers

In bdelloid rotifers, females reproduce exclusively by parthenogenesis (obligate parthenogenesis), while in monogonont rotifers, females can alternate between sexual and asexual reproduction (cyclical parthenogenesis). At least in one normally cyclical parthenogenetic species obligate parthenogenesis can be inherited: a recessive allele leads to loss of sexual reproduction in homozygous offspring.

Flatworms

At least two species of flatworms in the genus Dugesia, include polyploid individuals that reproduce by parthenogenesis. This type of parthenogenesis requires mating, but the sperm does not contribute to the genetics of the offspring (the parthenogenesis is pseudogamous, alternatively referred to as gynogenetic). A complex cycle of matings between diploid sexual and polyploid parthenogenetic individuals produces new parthenogenetic lines.

Snails

Several species of parthenogenetic gastropods have been studied, especially with respect to their status as invasive species. These include the New Zealand mud snail (Potamopyrgus antipodarum), the red-rimmed melania (Melanoides tuberculata), and the Quilted melania (Tarebia granifera).

Insects

Parthenogenesis in insects can cover a wide range of mechanisms. The offspring produced by parthenogenesis may be of both sexes, only female (thelytoky, e.g., aphids and some hymenopterans) or only male (arrhenotoky, e.g., most hymenopterans). Both true parthenogenesis and pseudogamy (gynogenesis or sperm-dependent parthenogenesis) are known to occur. The egg cells, depending on the species may be produced without meiosis (apomictically) or by one of the several automictic mechanisms.

A related phenomenon, polyembryony is a process that produces multiple clonal offspring from a single egg cell. This is known in some hymenopteran parasitoids and in Strepsiptera. In automictic species the offspring can be haploid or diploid. Diploids are produced by doubling or fusion of gametes after meiosis. Fusion is seen in the Phasmatodea, Hemiptera (Aleurodids and Coccidae), Diptera, and some Hymenoptera. In addition to these forms is hermaphroditism, where both the eggs and sperm are produced by the same individual, but is not a type of parthenogenesis. This is seen in three species of Icerya scale insects. Parasitic bacteria like Wolbachia induce automictic thelytoky in many insect species with haplodiploid systems. They cause gamete duplication in unfertilized eggs causing them to develop into female offspring.

Among species with the haplo-diploid sex-determination system, such as hymenopterans (ants, bees, and wasps) and thysanopterans (thrips), haploid males are produced from unfertilized eggs. Usually, eggs are laid only by the queen, but the unmated workers may also lay haploid, male eggs either regularly (e.g. stingless bees) or under special circumstances. An example of non-viable parthenogenesis is common among domesticated honey bees. The queen bee is the only fertile female in the hive; if she dies without the possibility of a viable replacement queen, it is not uncommon for the worker bees to lay eggs. This is a result of the lack of the queen's pheromones and the pheromones secreted by uncapped brood, which normally suppress ovarian development in workers. Worker bees are unable to mate, and the unfertilized eggs produce only drones (males), which can mate only with a queen. Thus, in a relatively short period, all the worker bees die off, and the new drones follow if they have not been able to mate before the collapse of the colony. This behavior is believed to have evolved to allow a doomed colony to produce drones which may mate with a virgin queen and thus preserve the colony's genetic progeny.

A few ants and bees are capable of producing diploid female offspring parthenogenetically. These include a honey bee subspecies from South Africa, Apis mellifera capensis, where workers are capable of producing diploid eggs parthenogenetically, and replacing the queen if she dies; other examples include some species of small carpenter bee, (genus Ceratina). Many parasitic wasps are known to be parthenogenetic, sometimes due to infections by Wolbachia.

The workers in five ant species and the queens in some ants are known to reproduce by parthenogenesis. In Cataglyphis cursor, a European formicine ant, the queens and workers can produce new queens by parthenogenesis. The workers are produced sexually.

In Central and South American electric ants, Wasmannia auropunctata, queens produce more queens through automictic parthenogenesis with central fusion. Sterile workers usually are produced from eggs fertilized by males. In some of the eggs fertilized by males, however, the fertilization can cause the female genetic material to be ablated from the zygote. In this way, males pass on only their genes to become fertile male offspring. This is the first recognized example of an animal species where both females and males can reproduce clonally resulting in a complete separation of male and female gene pools. As a consequence, the males only have fathers and the queens only mothers, while the sterile workers are the only ones with both parents of both sexes. These ants get the benefits of both asexual and sexual reproduction—the daughters who can reproduce (the queens) have all of the mother's genes, while the sterile workers whose physical strength and disease resistance are important are produced sexually.

Other examples of insect parthenogenesis can be found in gall-forming aphids (e.g., Pemphigus betae), where females reproduce parthenogenetically during the gall-forming phase of their life cycle and in grass thrips. In the grass thrips genus Aptinothrips there have been, despite the very limited number of species in the genus, several transitions to asexuality.

Crustaceans

Crustacean reproduction varies both across and within species. The water flea Daphnia pulex alternates between sexual and parthenogenetic reproduction. Among the better-known large decapod crustaceans, some crayfish reproduce by parthenogenesis. "Marmorkrebs" are parthenogenetic crayfish that were discovered in the pet trade in the 1990s. Offspring are genetically identical to the parent, indicating it reproduces by apomixis, i.e. parthenogenesis in which the eggs did not undergo meiosis. Spinycheek crayfish (Orconectes limosus) can reproduce both sexually and by parthenogenesis. The Louisiana red swamp crayfish (Procambarus clarkii), which normally reproduces sexually, has also been suggested to reproduce by parthenogenesis, although no individuals of this species have been reared this way in the lab. Artemia parthenogenetica is a species or series of populations of parthenogenetic brine shrimps.

Spiders

At least two species of spiders in the family Oonopidae (goblin spiders), Heteroonops spinimanus and Triaeris stenaspis, are thought to be parthenogenetic, as no males have ever been collected. Parthenogenetic reproduction has been demonstrated in the laboratory for T. stenaspis.

Sharks

Parthenogenesis in sharks has been confirmed in at least three species, the bonnethead, the blacktip shark, and the zebra shark.

A bonnethead, a type of small hammerhead shark, was found to have produced a pup, born live in 2001 at Henry Doorly Zoo in Nebraska, in a tank containing three female hammerheads, but no males. The pup was thought to have been conceived through parthenogenesis. It was concluded after DNA testing that the reproduction was parthenogenetic, as the female pup's DNA matched only one female who lived in the tank, and no male DNA was present in the pup. The pup was not a twin or clone of her mother, but rather, contained only half of her mother's DNA ("automictic parthenogenesis"). This type of reproduction had been seen before in bony fish, but not in cartilaginous fish such as sharks.

In the same year, a female Atlantic blacktip shark in Virginia reproduced via parthenogenesis. On 10 October 2008, scientists confirmed the second case of a "virgin birth" in a shark. The Journal of Fish Biology reported a study in which scientists said DNA testing proved that a pup carried by a female Atlantic blacktip shark in the Virginia Aquarium & Marine Science Center contained no genetic material from a male.

In 2002, two white-spotted bamboo sharks were born at the Belle Isle Aquarium in Detroit. They hatched 15 weeks after being laid in an aquarium containing only two female sharks.

In 2011, recurring shark parthenogenesis over several years was demonstrated in a captive zebra shark, a type of carpet shark. DNA genotyping demonstrated that individual zebra sharks can switch from sexual to parthenogenetic reproduction.

Rays

A female round stingray (Urobatis halleri) held in captivity from all males for eight years was reported pregnant in 2024. In June 2024, the aquarium where the ray resided reported that she was not pregnant, and instead had a rare reproductive disease.

Amphibians

Crocodiles

In June 2023, discovery was made at a zoo in Costa Rica, where researchers identified the first documented case of a self-pregnant crocodile. This female American crocodile, housed at Parque Reptilania, produced a genetically identical foetus, with a 99.9% similarity to herself. The scientists speculate that this unique ability might be inherited from an evolutionary ancestor, suggesting that even dinosaurs could have possessed the capability for self-reproduction. The 18-year-old crocodile laid the egg in January 2018, the fully formed foetus did not hatch and was stillborn. Notably, this crocodile had been kept separated from other crocodiles throughout her entire life since being acquired at the age of two.

Lizards and snakes

Most reptiles of the squamata (lizards and snakes) reproduce sexually, but parthenogenesis occurs naturally in certain whiptails, some geckos, rock lizards,Komodo dragons, and snakes. Some of these, like the mourning gecko Lepidodactylus lugubris, Indo-Pacific house gecko Hemidactylus garnotii, the hybrid whiptails Cnemidophorus, Caucasian rock lizards Darevskia, and the brahminy blindsnake, Indotyphlops braminus are unisexual and obligately parthenogenetic. Other reptiles, such as the Komodo dragon, other monitor lizards, and some species of boas, pythons, filesnakes, gartersnakes, and rattlesnakes were previously considered as cases of facultative parthenogenesis, but may be cases of accidental parthenogenesis.

In 2012, facultative parthenogenesis was reported in wild vertebrates for the first time by US researchers amongst captured pregnant copperhead and cottonmouth female pit-vipers. The Komodo dragon, which normally reproduces sexually, has also been found able to reproduce asexually by parthenogenesis. A case has been documented of a Komodo dragon reproducing via sexual reproduction after a known parthenogenetic event, highlighting that these cases of parthenogenesis are reproductive accidents, rather than adaptive, facultative parthenogenesis.

Some reptile species use a ZW chromosome system, which produces either males (ZZ) or females (ZW). Until 2010, it was thought that the ZW chromosome system used by reptiles was incapable of producing viable WW offspring, but a (ZW) female boa constrictor was discovered to have produced viable female offspring with WW chromosomes.

Parthenogenesis has been studied extensively in the New Mexico whiptail in the genus Aspidoscelis of which 15 species reproduce exclusively by parthenogenesis. These lizards live in the dry and sometimes harsh climate of the southwestern United States and northern Mexico. All these asexual species appear to have arisen through the hybridization of two or three of the sexual species in the genus leading to polyploid individuals. The mechanism by which the mixing of chromosomes from two or three species can lead to parthenogenetic reproduction is unknown. Recently, a hybrid parthenogenetic whiptail lizard was bred in the laboratory from a cross between an asexual and a sexual whiptail. Because multiple hybridization events can occur, individual parthenogenetic whiptail species can consist of multiple independent asexual lineages. Within lineages, there is very little genetic diversity, but different lineages may have quite different genotypes.

An interesting aspect to reproduction in these asexual lizards is that mating behaviors are still seen, although the populations are all female. One female plays the role played by the male in closely related species, and mounts the female that is about to lay eggs. This behaviour is due to the hormonal cycles of the females, which cause them to behave like males shortly after laying eggs, when levels of progesterone are high, and to take the female role in mating before laying eggs, when estrogen dominates. Lizards who act out the courtship ritual have greater fecundity than those kept in isolation, due to the increase in hormones that accompanies the mounting. So, although the populations lack males, they still require sexual behavioral stimuli for maximum reproductive success.

Some lizard parthenogens show a pattern of geographic parthenogenesis, occupying high mountain areas where their ancestral forms have an inferior competition ability. In Caucasian rock lizards of genus Darevskia, which have six parthenogenetic forms of hybrid origin hybrid parthenogenetic form D. "dahli" has a broader niche than either of its bisexual ancestors and its expansion throughout the Central Lesser Caucasus caused decline of the ranges of both its maternal and paternal species.

Birds

Parthenogenesis in birds is known mainly from studies of domesticated turkeys and chickens, although it has also been noted in the domestic pigeon. In most cases the egg fails to develop normally or completely to hatching. The first description of parthenogenetic development in a passerine was demonstrated in captive zebra finches, although the dividing cells exhibited irregular nuclei and the eggs did not hatch.

Parthenogenesis in turkeys appears to result from a conversion of haploid cells to diploid; most embryos produced in this way die early in development. Rarely, viable birds result from this process, and the rate at which this occurs in turkeys can be increased by selective breeding, but male turkeys produced from parthenogenesis have smaller testes and reduced fertility.

In 2021, the San Diego Zoo reported that they had two unfertilized eggs from their California condor breeding program hatch. This is the first known example of parthenogenesis in this species, as well as one of the only known examples of parthenogenesis happening where males are still present.

Mammals

There are no known cases of naturally occurring mammalian parthenogenesis in the wild. Parthenogenetic progeny of mammals would have two X chromosomes, and would therefore be genetically female. In 1936, Gregory Goodwin Pincus inducing parthenogenesis in a rabbit. In 2004, scientists at Tokyo University of Agriculture used parthenogenesis to create a fatherless mouse. Using gene targeting, they were able to manipulate two imprinted loci H19/IGF2 and DLK1/MEG3 to produce bi-maternal mice at high frequency and subsequently show that fatherless mice have enhanced longevity.

References

1. Heesch, Svenja; Serrano-Serrano, Martha; Barrera-Redondo, Josué; Luthringer, Rémy; Peters, Akira F.; Destombe, Christophe; et al. (July 2021). "Evolution of life cycles and reproductive traits: Insights from the brown algae". Journal of Evolutionary Biology. 34 (7): 992–1009. doi:10.1111/jeb.13880. PMID 34096650. S2CID 92334399.
2. Preston, Elizabeth (13 February 2024). "Self-love is important, but we mammals are stuck with sex". The New York Times. Archived from the original on 13 February 2024. Retrieved 16 February 2024. Some female birds, reptiles, and other animals can make a baby on their own. But for mammals like us, eggs and sperm need each other.
3. Hurtado-Gonzales, O. P.; Lamour, K. H. (2009). "Evidence for inbreeding and apomixis in close crosses of Phytophthora capsici". Plant Pathology. 58 (4): 715–722. doi:10.1111/j.1365-3059.2009.02059.x.
4. Read, V. M. St. J. (July 1988). "The Onychophora of Trinidad, Tobago, and the Lesser Antilles". Zoological Journal of the Linnean Society. 93 (3): 225–257. doi:10.1111/j.1096-3642.1988.tb01362.x.
5. "Bdelloids: No sex for over 40 million years". TheFreeLibrary. ScienceNews. Retrieved 30 April 2011.
6. Stelzer, C.-P.; Schmidt, J.; Wiedlroither, A.; Riss, S. (2010). "Loss of Sexual Reproduction and Dwarfing in a Small Metazoan". PLOS ONE. 5 (9): e12854. Bibcode:2010PLoSO...512854S. doi:10.1371/journal.pone.0012854. PMC 2942836. PMID 20862222.
7. Lentati, G. Benazzi (1966). "Amphimixis and pseudogamy in fresh-water triclads: Experimental reconstitution of polyploid pseudogamic biotypes". Chromosoma. 20: 1–14. doi:10.1007/BF00331894. S2CID 21654518.
8. Wallace, C. (1992). "arthenogenesis, sex and chromosomes in Potamopyrgus". Journal of Molluscan Studies. 58 (2): 93–107. doi:10.1093/mollus/58.2.93.
9. Ben-Ami, F.; Heller, J. (2005). "Spatial and temporal patterns of parthenogenesis and parasitism in the freshwater snail Melanoides tuberculata". Journal of Evolutionary Biology. 18 (1): 138–146. doi:10.1111/j.1420-9101.2004.00791.x. PMID 15669970. S2CID 10422561.
10. Miranda, Nelson A. F.; Perissinotto, Renzo; Appleton, Christopher C.; Lalueza-Fox, Carles (2011). "Population Structure of an Invasive Parthenogenetic Gastropod in Coastal Lakes and Estuaries of Northern KwaZulu-Natal, South Africa". PLOS ONE. 6 (8): e24337. Bibcode:2011PLoSO...624337M. doi:10.1371/journal.pone.0024337. PMC 3164166. PMID 21904629.
11. ^ Kirkendall, L. R. & Normark, B. (2003) "Parthenogenesis" in Encyclopaedia of Insects (Vincent H. Resh and R. T. Carde, Eds.) Academic Press. pp. 851–856
12. Copeland, Claudia S.; Hoy, Marjorie A.; Jeyaprakash, Ayyamperumal; Aluja, Martin; Ramirez-Romero, Ricardo; Sivinski, John M. (1 September 2010). "Genetic Characteristics of Bisexual and Female-Only Populations of Odontosema anastrephae (Hymenoptera: Figitidae)". Florida Entomologist. 93 (3): 437–443. doi:10.1653/024.093.0318.
13. Bell, G. (1982). The Masterpiece of Nature: The Evolution and Genetics of Sexuality, University of California Press, Berkeley, pp. 1–635 (see p. 295). ISBN 978-0-520-04583-5
14. ^ Pearcy, M.; Aron, S; Doums, C.; Keller, L (2004). "Conditional Use of Sex and Parthenogenesis for Worker and Queen Production in Ants". Science. 306 (5702): 1780–1783. Bibcode:2004Sci...306.1780P. doi:10.1126/science.1105453. PMID 15576621. S2CID 37558595.
15. ^ Fournier, Denis; Estoup, Arnaud; Orivel, Jérôme; Foucaud, Julien; Jourdan, Hervé; Le Breton, Julien Le; Keller, Laurent (2005). "Clonal reproduction by males and females in the little fire ant" (PDF). Nature. 435 (7046): 1230–1234. Bibcode:2005Natur.435.1230F. doi:10.1038/nature03705. PMID 15988525. S2CID 1188960.
16. CJ van der Kooi & T Schwander (2014) "Evolution of asexuality via different mechanisms in grass thrips (Thysanoptera: Aptinothrips)" Evolution 86:1883–1893
17. Eads, Brian D.; Colbourne, John K.; Bohuski, Elizabeth; Andrews, Justen (2007). "Profiling sex-biased gene expression during parthenogenetic reproduction in Daphnia pulex". BMC Genomics. 8: 464. doi:10.1186/1471-2164-8-464. PMC 2245944. PMID 18088424.
18. Scholtz, Gerhard; Braband, Anke; Tolley, Laura; Reimann, André; Mittmann, Beate; Lukhaup, Chris; et al. (2003). "Parthenogenesis in an outsider crayfish". Ecology. Nature. 421 (6925): 806. Bibcode:2003Natur.421..806S. doi:10.1038/421806a. PMID 12594502. S2CID 84740187.
19. Martin, Peer; Kohlmann, Klaus; Scholtz, Gerhard (2007). "The parthenogenetic Marmorkrebs (marbled crayfish) produces genetically uniform offspring". Naturwissenschaften. 94 (10): 843–846. Bibcode:2007NW.....94..843M. doi:10.1007/s00114-007-0260-0. PMID 17541537. S2CID 21568188.
20. Buřič, Miloš; Hulák, Martin; Kouba, Antonín; Petrusek, Adam; Kozák, Pavel; Etges, William J. (31 May 2011). "A successful crayfish invader is capable of facultative parthenogenesis: A novel reproductive mode in decapod crustaceans". PLoS One. 6 (5): e20281. Bibcode:2011PLoSO...620281B. doi:10.1371/journal.pone.0020281. PMC 3105005. PMID 21655282.
21. Yue GH, Wang GL, Zhu BQ, Wang CM, Zhu ZY, Lo LC (2008). "Discovery of four natural clones in a crayfish species Procambarus clarkii". International Journal of Biological Sciences. 4 (5): 279–282. doi:10.7150/ijbs.4.279. PMC 2532795. PMID 18781225.
22. Muñoz, Joaquín; Gómez, Africa; Green, Andy J.; Figuerola, Jordi; Amat, Francisco; Rico, Ciro; Moreau, Corrie S. (4 August 2010). "Evolutionary origin and phylogeography of the diploid obligate parthenogen Artemia parthenogenetica (Branchiopoda: Anostraca)". PLoS One. 5 (8): e11932. Bibcode:2010PLoSO...511932M. doi:10.1371/journal.pone.0011932. PMC 2915914. PMID 20694140.
23. Korenko, Stanislav; Šmerda, Jakub; Pekár, Stano (2009). "Life-history of the parthenogenetic oönopid spider, Triaeris stenaspis (Araneae: Oonopidae)". European Journal of Entomology. 106 (2): 217–223. doi:10.14411/eje.2009.028. Retrieved 2016-04-30.
24. Chapman, Demian D.; Shivji, Mahmood S.; Louis, Ed; Sommer, Julie; Fletcher, Hugh; Prodöhl, Paulo A. (2007). "Virgin birth in a hammerhead shark". Biology Letters. 3 (4): 425–427. doi:10.1098/rsbl.2007.0189. PMC 2390672. PMID 17519185.
25. ^ Chapman, D.D.; Firchau, B.; Shivji, M. S. (2008). "Parthenogenesis in a large-bodied requiem shark, the blacktip". Journal of Fish Biology. 73 (6): 1473–1477. doi:10.1111/j.1095-8649.2008.02018.x.
26. ^ Robinson, D.P.; Baverstock, W.; Al-Jaru, A.; Hyland, K.; Khazanehdari, K.A. (2011). "Annually recurring parthenogenesis in a zebra shark Stegostoma fasciatum". Journal of Fish Biology. 79 (5): 1376–1382. Bibcode:2011JFBio..79.1376R. doi:10.1111/j.1095-8649.2011.03110.x. PMID 22026614.
27. "Captive shark had 'virgin birth'". BBC News. 2007-05-23. Retrieved 2008-12-23.
28. "'Virgin birth' for aquarium shark". Metro.co.uk. 2008-10-10. Retrieved 2008-10-10.
29. "Shark gives virgin birth in Detroit". National Geographic. September 2002. Archived from the original on 2002-09-29. Retrieved 17 April 2010.
30. "First virgin birth of zebra shark in Dubai". Sharkyear.com. 12 December 2011.
31. Dudgeon, Christine L.; Coulton, Laura; Bone, Ren; Ovenden, Jennifer R.; Thomas, Severine (2017-01-16). "Switch from sexual to parthenogenetic reproduction in a zebra shark". Scientific Reports. 7: 40537. Bibcode:2017NatSR...740537D. doi:10.1038/srep40537. PMC 5238396. PMID 28091617.
32. Hewson, Georgie (2024-02-14). "Charlotte the stingray due to give birth within weeks despite no male ray company for years". Australian Broadcasting Corporation. Retrieved 2024-02-17.
33. Chappell, Bill (2024-06-04). "After saying Charlotte, a lone stingray, was pregnant, aquarium now says she's sick". NPR.org. NPR. Retrieved 2024-06-05.
34. "Crocodile found to have made herself pregnant". BBC News. 2023-06-07. Retrieved 2023-06-07.
35. Booth, Warren; Levine, Brenna A.; Corush, Joel B.; Davis, Mark A.; Dwyer, Quetzal; De Plecker, Roel; Schuett, Gordon W. (June 2023). "Discovery of facultative parthenogenesis in a new world crocodile". Biology Letters. 19 (6). doi:10.1098/rsbl.2023.0129. hdl:10919/117182. PMC 10244963. PMID 37282490.
36. Halliday, Tim R. (1986). Kraig Adler (ed.). Reptiles & Amphibians. Torstar Books. p. 101. ISBN 978-0-920269-81-7.
37. ^ Darevskii IS. 1967. Rock lizards of the Caucasus: systematics, ecology and phylogenesis of the polymorphic groups of Caucasian rock lizards of the subgenus Archaeolacerta. Nauka: Leningrad .
38. ^ Tarkhnishvili, D.N. (2012). "Evolutionary history, habitats, diversification, and speciation in Caucasian rock lizards". In Jenkins, O.P. (ed.). Advances in Zoology Research. Vol. 2. Hauppauge, N.Y.: Nova Science Publishers. pp. 79–120.
39. Watts, P.C.; Buley, K.R.; Sanderson, S.; Boardman, W.; Ciofi, C.; Gibson, R. (2006). "Parthenogenesis in Komodo dragons". Nature. 444 (7122): 1021–1022. Bibcode:2006Natur.444.1021W. doi:10.1038/4441021a. PMID 17183308. S2CID 4311088.
40. "Self-impregnated snake in Missouri has another 'virgin birth'". UPI.com. United Press International. 21 September 2015. Retrieved 3 October 2015.
41. Wiechmann, R. (2012). "Observations of parthenogenesis in monitor lizards" (PDF). Biawak. 6 (1): 11–21.
42. Booth, W.; Johnson, D.H.; Moore, S.; Schal, C.; Vargo, E.L. (2010). "Evidence for viable, non-clonal but fatherless boa constrictors". Biology Letters. 7 (2): 253–256. doi:10.1098/rsbl.2010.0793. PMC 3061174. PMID 21047849.
43. Booth, Warren; Larry Million; R. Graham Reynolds; Gordon M. Burghardt; Edward L. Vargo; Coby Schal; Athanasia C. Tzika; Gordon W. Schuett (December 2011). "Consecutive Virgin Births in the New World Boid Snake, the Colombian Rainbow Boa, Epicrates maurus". Journal of Heredity. 102 (6): 759–763. CiteSeerX 10.1.1.414.384. doi:10.1093/jhered/esr080. PMID 21868391.
44. Kinney, M.E.; Wack, R.F.; Grahn, R.A.; Lyons, L. (2013). "Parthenogenesis in a Brazilian rainbow boa (Epicrates cenchria cenchria)". Zoo Biology. 32 (2): 172–176. doi:10.1002/zoo.21050. PMID 23086743.
45. Groot, T. V. M.; E Bruins; J. A. J. Breeuwer (2003-02-28). "Molecular genetic evidence for parthenogenesis in the Burmese python, Python molars bivittatus". Heredity. 90 (2): 130–135. CiteSeerX 10.1.1.578.4368. doi:10.1038/sj.hdy.6800210. PMID 12634818. S2CID 2972822.
46. Shepherd, Kyle (18 December 2014). "A virgin snake birth" (Press release).
47. Magnusson, W.E. (1979). "Production of an embryo by an Acrochordus javanicus isolated for seven years". Copeia. 1979 (4): 744–745. doi:10.2307/1443886. JSTOR 1443886.
48. Dubach, J.; Sajewicz, A.; Pawley, R. (1997). "Parthenogenesis in the Arafura filesnake (Acrochordus arafurae)". Herpetological Natural History. 5 (1): 11–18.
49. Reynolds, R.G.; Booth, W.; Schuett, G.W.; Fitzpatrick, B.M.; Burghardt, G.M. (2012). "Successive virgin births of viable male progeny in the checkered gartersnake, Thamnophis marcianus". Biological Journal of the Linnean Society. 107 (3): 566–572. doi:10.1111/j.1095-8312.2012.01954.x.
50. Schuett, G.W.; Fernandez, P.J.; Gergits, W.F.; Casna, N.J.; Chiszar, D.; Smith, H.M.; et al. (1997). "Production of offspring in the absence of males: Evidence for facultative parthenogenesis in bisexual snakes". Herpetological Natural History. 5 (1): 1–10.
51. Schuett, G.W.; Fernandez, P.J.; Chiszar, D.; Smith, H.M. (1998). "Fatherless sons: A new type of parthenogenesis in snakes". Fauna. 1 (3): 20–25.
52. ^ van der Kooi, C.J.; Schwander, T. (2015). "Parthenogenesis: Birth of a new lineage or reproductive accident?" (PDF). Current Biology. 25 (15): R659–R661. Bibcode:2015CBio...25.R659V. doi:10.1016/j.cub.2015.06.055. PMID 26241141.
53. "Virgin births discovered in wild snakes". BBC Nature. 12 September 2012. Archived from the original on 13 September 2012. Retrieved 2012-09-12.
54. Highfield, Roger (21 December 2006). "No sex please, we're lizards". The Daily Telegraph. Archived from the original on 2007-10-11.
55. "Virgin birth of dragons". The Hindu. 25 January 2007. Archived from the original on 2007-10-01. Retrieved 3 February 2007.
56. Walker, Matt (2010-11-03). "Snake has unique 'virgin birth'". BBC News.
57. Lutes, Aracely A.; Baumann, Diana P.; Neaves, William B.; Baumann, Peter (2011-06-14). "Laboratory synthesis of an independently reproducing vertebrate species". Proceedings of the National Academy of Sciences of the USA. 108 (24): 9910–9915. Bibcode:2011PNAS..108.9910L. doi:10.1073/pnas.1102811108. PMC 3116429. PMID 21543715.
58. Crews, D.; Grassman, M.; Lindzey, J. (1986). "Behavioral facilitation of reproduction in sexual and unisexual whiptail lizards". Proceedings of the National Academy of Sciences. 83 (24): 9547–9550. Bibcode:1986PNAS...83.9547C. doi:10.1073/pnas.83.24.9547. PMC 387177. PMID 3467325.
59. Vrijenhoek, R.C.; Parker, E.D. (2009). "Geographical parthenogenesis: General purpose genotypes and frozen niche variation". In Schön I; Martens K.; van Dijk P. (eds.). Lost Sex. Berlin, Germany: Springer Publications. pp. 99–131.
60. Murphy, R.W.; Darevsky, I.S.; MacCulloch, R.D.; Fu, J.; Kupriyanova, L.A.; Upton, D.E.; Danielyan, F. (1997). "Old age, multiple formations or genetic plasticity? Clonal diversity in a parthenogenetic Caucasian rock lizard, Lacerta dahli". Genetica. 101 (2): 125–130. doi:10.1023/A:1018392603062. PMID 16220367. S2CID 11145792.
61. Tarkhnishvili, D.; Gavashelishvili, A.; Avaliani, A.; Murtskhvaladze, M.; Mumladze, L. (2010). "Unisexual rock lizard might be outcompeting its bisexual progenitors in the Caucasus". Biological Journal of the Linnean Society. 101 (2): 447–460. doi:10.1111/j.1095-8312.2010.01498.x.
62. ^ Schut, E.; Hemmings, N.; Birkhead, T.R. (2008). "Parthenogenesis in a passerine bird, the Zebra finch Taeniopygia guttata". Ibis. 150 (1): 197–199. doi:10.1111/j.1474-919x.2007.00755.x.
63. ^ Mittwoch, U. (1978). "Parthenogenesis". Journal of Medical Genetics. 15 (3): 165–181. doi:10.1136/jmg.15.3.165. PMC 1013674. PMID 353283.
64. Nestor, Karl (2009). "Parthenogenesis in turkeys". The Tremendous Turkey. oardc.ohio-state.edu/4h. 4H / Poultry. Ohio State University. Archived from the original on 2010-07-14.
65. Sarvella, P. (1974). "Testes structure in normal and parthenogenetic turkeys". The Journal of Heredity. 65 (5): 287–290. doi:10.1093/oxfordjournals.jhered.a108530. PMID 4373503.
66. Ryder, Oliver A.; Thomas, Steven; Judson, Jessica Martin; Romanov, Michael N.; Dandekar, Sugandha; Papp, Jeanette C.; et al. (2021-12-17). "Facultative parthenogenesis in California condors". Journal of Heredity. 112 (7): 569–574. doi:10.1093/jhered/esab052. PMC 8683835. PMID 34718632.
67. Pincus, Gregory (2018). The Eggs of Mammals. New York, NY: The Macmillan Company – via Internet Archive.
68. Kawahara, Manabu; Wu, Qiong; Takahashi, Nozomi; Morita, Shinnosuke; Yamada, Kaori; Ito, Mitsuteru; et al. (2007). "High-frequency generation of viable mice from engineered bi-maternal embryos". Nature Biotechnology. 25 (9): 1045–1050. doi:10.1038/nbt1331. PMID 17704765. S2CID 7242745.
69. Kawahara, M.; Kono, T. (2009). "Longevity in mice without a father". Human Reproduction. 25 (2): 457–461. doi:10.1093/humrep/dep400. PMID 19952375.

• Asexual reproduction in animals